SmogRank / History / Country race
Countries, worst air first, day by day
Each country's typical measured city over the 30 days to every day since January 2023, worst first. Press Play to watch the order change, or drag the slider to any day.
The worst countries for PM2.5 over the 30 days to 25 Feb 2024: Pakistan 74.8 µg/m³, India 70.9 µg/m³ and China 50.7 µg/m³.
- 1Pakistan3 cities74.8
- 2India5 cities70.9
- 3China3 cities50.7
- 4North Macedonia9 cities40.1
- 5Thailand77 cities, was 937.3
- 6Serbia18 cities36.8
- 7Montenegro3 cities35.8
- 8Italy40 cities28.4
- 9Romania10 cities19.1
- 10Chile45 cities18.8
- 11Greece9 cities18.1
- 12Bulgaria6 cities17.7
- 13Peru6 cities17.4
- 14Hong Kong13 cities17.3
- 15Poland78 cities16.1
- 16South Africa8 cities15.8
- 17Slovakia42 cities15.2
- 18Mexico13 cities13.7
- 19Hungary10 cities12.9
- 20Latvia4 cities12.6
+ 23 more countries, the next at 11.9 µg/m³
- 37United States786 cities6.7
Not counted on this day, too few cities measured: Reunion since 20 Jan 2024 and Malta since 6 Jan 2024. Days missing from the source archive fall in this window, so fewer countries are counted.
Countries counted each day
A country's number is its typical measured city: the median of its cities' means over the 30 days (a city needs 21 of them measured; 5 of 7 on the 7-day race), shown only with 3 such cities. A country whose monitors go quiet fades out where it stood rather than sliding down, so a gap never reads as cleaner air; "was" beside a city count marks a month after many cities joined or left. Some large countries are thin or missing because their monitors' licences don't allow reuse. How we rank.
Not covered: the government monitoring networks of China, Turkey and Iran, which publish only on their own websites. We are building the reader for China's network. The networks of Turkey and Iran don't answer requests from outside their countries, so we can't read them. Most cities there are missing from this board, not clean. Why.